638940672 has 120 divisors (see below), whose sum is σ = 1854093384. Its totient is φ = 211820544.

The previous prime is 638940637. The next prime is 638940689. The reversal of 638940672 is 276049836.

638940672 is a `hidden beast` number, since 638 + 9 + 4 + 0 + 6 + 7 + 2 = 666.

It is a super-3 number, since 3×638940672³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1442083 + ... + 1442525.

Almost surely, 2^638940672 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638940672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (927046692).

638940672 is an abundant number, since it is smaller than the sum of its proper divisors (1215152712).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638940672 is a wasteful number, since it uses less digits than its factorization.

638940672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 780 (or 761 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 45.

The square root of 638940672 is about 25277.2758025860. The cubic root of 638940672 is about 861.2981440658.

The spelling of 638940672 in words is "six hundred thirty-eight million, nine hundred forty thousand, six hundred seventy-two".